Hi forum,
I'm new (to aac in particular, and ee in general), so have mercy.
I need to be able to remotely (as in, from another city, not from across the room) toggle power to one of the internal 12V lines (i.e., molex power cables) supplied by the PSU in my PC. USB control of the line would be preferred, but I'd be happy with RS-232 for starters (and I have no parallel port on the PC).
Googling turned up these similar projects:
http://schmail.com/dslmon/
http://www.windmeadow.com/node/4
Attached is the circuit I worked out, based upon the 2 schematics above.
Parts list:
Reed Relay SPST 12VDC 0.5A @ 125VAC (Radio Shack #275-233)
Rectifier Diode 1N4004 (Radio Shack #276-1103)
NPN Switching Transistor 2N2222 (Radio Shack #276-1617)
4.7k-Ohm Resistor (Radio Shack #271-1330)
I'm controlling the DTR pin with a C prog. When I set it high, I get +10V out of the pin, otherwise (pin set low), -11V. What should I see going into the relay? My concern is that I don't have enough juice going to the coil to trigger the switch, but I'm not even sure I have my relay wired properly.
And if there is a better way to do this, I'm all ears! Unless it is some OTS gizmo that sets me back serious coin. This _should_ be a simple gadget, so I prefer the DIY way.
tia,
bill
I'm new (to aac in particular, and ee in general), so have mercy.
I need to be able to remotely (as in, from another city, not from across the room) toggle power to one of the internal 12V lines (i.e., molex power cables) supplied by the PSU in my PC. USB control of the line would be preferred, but I'd be happy with RS-232 for starters (and I have no parallel port on the PC).
Googling turned up these similar projects:
http://schmail.com/dslmon/
http://www.windmeadow.com/node/4
Attached is the circuit I worked out, based upon the 2 schematics above.
Parts list:
Reed Relay SPST 12VDC 0.5A @ 125VAC (Radio Shack #275-233)
Rectifier Diode 1N4004 (Radio Shack #276-1103)
NPN Switching Transistor 2N2222 (Radio Shack #276-1617)
4.7k-Ohm Resistor (Radio Shack #271-1330)
I'm controlling the DTR pin with a C prog. When I set it high, I get +10V out of the pin, otherwise (pin set low), -11V. What should I see going into the relay? My concern is that I don't have enough juice going to the coil to trigger the switch, but I'm not even sure I have my relay wired properly.
And if there is a better way to do this, I'm all ears! Unless it is some OTS gizmo that sets me back serious coin. This _should_ be a simple gadget, so I prefer the DIY way.
tia,
bill
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